Novel small punch testing method and its application to conversion of mechanical properties for aerospace materials

For the small punch test with the advantage of slightly damaged sampling, a theoretical model was derived based on the energy density equivalence principle to describe the relationships among the load, displacement, geometric size, and uniaxial mechanical law parameters. A novel small punch test method was then proposed for aerospace materials to convert mechanical properties between uniaxial tensile test results and small punch test results. Small punch tests and uniaxial tensile tests were carried out on five aerospace materials. The results show that the stress-strain curves obtained by the new method were in close agreement with those obtained by uniaxial tensile tests; the relative errors of the elastic moduli obtained by the new method results and the uniaxial tensile test results were within 10%; and the relative errors of the yield strengths and tensile strengths obtained by the two methods were mostly within 5%. The proposed method is expected to promote the application of SPT for the safety evaluation of in-service structures.